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<div><a href="../index.html">Home</a> &gt;  <a href="index.html">fvcom_prepro</a> &gt; estimate_ts.m</div>

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<h1>estimate_ts
</h1>

<h2><a name="_name"></a>PURPOSE <a href="#_top"><img alt="^" border="0" src="../up.png"></a></h2>
<div class="box"><strong>Estimate time step at each node</strong></div>

<h2><a name="_synopsis"></a>SYNOPSIS <a href="#_top"><img alt="^" border="0" src="../up.png"></a></h2>
<div class="box"><strong>function [Mobj] = estimate_ts(Mobj) </strong></div>

<h2><a name="_description"></a>DESCRIPTION <a href="#_top"><img alt="^" border="0" src="../up.png"></a></h2>
<div class="fragment"><pre class="comment"> Estimate time step at each node  

 [Mobj] = function estimate_ts(Mobj)  

 DESCRIPTION:
    Calculate barotropic time step 

 INPUT
    Mobj = matlab mesh object

 OUTPUT:
    Mobj = matlab structure containing mesh time step

 EXAMPLE USAGE
    Mobj = estimate_ts(Mobj)

 Author(s):  
    Geoff Cowles (University of Massachusetts Dartmouth)

 Revision history
   
==============================================================================</pre></div>

<!-- crossreference -->
<h2><a name="_cross"></a>CROSS-REFERENCE INFORMATION <a href="#_top"><img alt="^" border="0" src="../up.png"></a></h2>
This function calls:
<ul style="list-style-image:url(../matlabicon.gif)">
</ul>
This function is called by:
<ul style="list-style-image:url(../matlabicon.gif)">
<li><a href="example.html" class="code" title="">example</a>	example demonstrating reading in a 2DM file and constructing a model</li></ul>
<!-- crossreference -->



<h2><a name="_source"></a>SOURCE CODE <a href="#_top"><img alt="^" border="0" src="../up.png"></a></h2>
<div class="fragment"><pre>0001 <a name="_sub0" href="#_subfunctions" class="code">function [Mobj] = estimate_ts(Mobj) </a>
0002 
0003 <span class="comment">% Estimate time step at each node</span>
0004 <span class="comment">%</span>
0005 <span class="comment">% [Mobj] = function estimate_ts(Mobj)</span>
0006 <span class="comment">%</span>
0007 <span class="comment">% DESCRIPTION:</span>
0008 <span class="comment">%    Calculate barotropic time step</span>
0009 <span class="comment">%</span>
0010 <span class="comment">% INPUT</span>
0011 <span class="comment">%    Mobj = matlab mesh object</span>
0012 <span class="comment">%</span>
0013 <span class="comment">% OUTPUT:</span>
0014 <span class="comment">%    Mobj = matlab structure containing mesh time step</span>
0015 <span class="comment">%</span>
0016 <span class="comment">% EXAMPLE USAGE</span>
0017 <span class="comment">%    Mobj = estimate_ts(Mobj)</span>
0018 <span class="comment">%</span>
0019 <span class="comment">% Author(s):</span>
0020 <span class="comment">%    Geoff Cowles (University of Massachusetts Dartmouth)</span>
0021 <span class="comment">%</span>
0022 <span class="comment">% Revision history</span>
0023 <span class="comment">%</span>
0024 <span class="comment">%==============================================================================</span>
0025 
0026 subname = <span class="string">'estimate_ts'</span>;
0027 <span class="keyword">global</span> ftbverbose
0028 <span class="keyword">if</span>(ftbverbose)
0029   fprintf(<span class="string">'\n'</span>)
0030   fprintf([<span class="string">'begin : '</span> subname <span class="string">'\n'</span>])
0031 <span class="keyword">end</span>;
0032 
0033 <span class="comment">%------------------------------------------------------------------------------</span>
0034 <span class="comment">% Set constants</span>
0035 <span class="comment">%------------------------------------------------------------------------------</span>
0036 
0037 g    = 9.81; <span class="comment">%gravitational acceleration</span>
0038 u    = 3.0;  <span class="comment">%u-velocity</span>
0039 zeta = 3.0;  <span class="comment">%tide amp</span>
0040 
0041 <span class="keyword">if</span>(~Mobj.have_bath)
0042     error(<span class="string">'can''t estimate the time step without bathymetry'</span>)
0043 <span class="keyword">end</span>;
0044 
0045 <span class="comment">%------------------------------------------------------------------------------</span>
0046 <span class="comment">% Compute the time step estimate</span>
0047 <span class="comment">%------------------------------------------------------------------------------</span>
0048 x = Mobj.x;
0049 y = Mobj.y;
0050 h = Mobj.h;
0051 tri = Mobj.tri;
0052 nVerts = Mobj.nVerts;
0053 nElems = Mobj.nElems;
0054 
0055 ts = ones(nVerts,1)*1e9;
0056 side = zeros(nVerts,1);
0057 <span class="keyword">for</span> i=1:nElems
0058   n1 = tri(i,1);
0059   n2 = tri(i,2);
0060   n3 = tri(i,3);
0061   nds = [n1 n2 n3];
0062   lside = sqrt( (x(n1)-x(n2))^2 + (y(n1)-y(n2))^2); 
0063   dpth  = max(h(nds))+zeta;
0064   dpth  = max(dpth,1.);
0065   ts(nds) = min(ts(nds),lside/( sqrt(g*dpth) + u));
0066 <span class="keyword">end</span>;
0067 <span class="keyword">if</span>(ftbverbose); fprintf(<span class="string">'minimum time step: %f seconds\n'</span>,min(ts)); <span class="keyword">end</span>;
0068 Mobj.ts = ts;
0069 Mobj.have_ts = true;
0070 
0071 <span class="keyword">if</span>(ftbverbose)
0072   fprintf([<span class="string">'end   : '</span> subname <span class="string">'\n'</span>])
0073 <span class="keyword">end</span>;</pre></div>
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